The present invention generally relates to suture anchors. Specifically, the invention relates to suture anchors used in securing soft tissue to bone.
Soft tissues, such as tendons and ligaments generally insert into bone through small collagenous fibers called sharpey's fibers. These connections are strong and permit the muscle which pull on the tendons to effect force on the bones, or the ligaments which stabilize the body's joints, the resist force. When a tissue is tom away from the bone and requires repair, the surgeon is often required to fashion tunnels into the bone through which to pass sutures, which are then threaded through the soft tissues. The bone tunnels are often difficult to make, and generally require large open incisions. Recently, through the advent of endoscopic surgery, where the surgeon looks into a joint cavity with a telescope, there has been a desire to repair soft tissues back to bone without performing a large open incision. The device described herein facilitates that procedure.
A variety of devices are available for attaching objects to bone, such as screws, staples, cement, and sutures alone. These devices have been used to attach soft tissue, such as ligaments, tendons, muscles, as well as objects such as prostheses, to bone. Screws tend to loosen with time, usually requires a second operation to remove the loosened screw. In addition, conventional screws tend to be time-consuming and difficult to install, especially in a tight space such as that encountered during endoscopic surgery.
Installation of presently available bone screws involves several steps. First, a pilot hole must normally be drilled into the bone. Then, depending on the bone structure, the bone may also have to be tapped to accept to the screw. The screw is next positioned and turned to fasten. Finally, if the suture is not pre-attached, the suture is threaded into an eyelet contained in the screw. This multi-step process, necessitated by the structure of available bone screw devices, is difficult for the surgeon, especially in confined surgical areas. Often, such accessibility considerations limit the ability of the surgeon to secure sutures at optimal locations, forcing the surgeon to select a less-than-desirable location. Furthermore, the final position of the screw is determined once the hole has been drilled, making it difficult to relocate or position the screw in a different position.
U.S. Pat. No. 4,632,100 discloses a cylindrical suture anchor which includes a drill at a first end (for boring a hole in a bone) and a flight of threads on the other end, and distal from the drill, for securing the anchor in a hole established by the drill. Sutures are held in the interior of the anchor by means of an annular disc that is press fit into the interior of the anchor. This two piece assembly is difficult to assemble and, due to the suture-holding disc, is substantially limited in the number of sutures that can be held. Moreover, the discrete drill and thread flights are inefficient in their operation.
Staples are disadvantageous for some of the same reasons as standard screws, plus there are additional set-backs for using staples for attachment. Staples have been known to crack the bone during deployment, or to accidentally transect the object being attached to the bone.
Other devices that currently exist for attaching soft tissue to bone include metal screws with sutures attached, shaped metal anchors through which sutures can be threaded, and plastic tacks with sutures attached. Each of these devices includes a single suture affixed to the device prior to implantation. These devices are difficult to deploy endoscopically and are limited to single sutures even though multiple sutures are often required for soft tissue repair.
Accordingly, it is an object of the invention to provide a device that is designed for endoscopic use and that accommodates multiple suture fixation.